i love lucas

i love lucas

Atoms

an atoms is the basic particle from which elements are made

structure of an atom

positively charged nucleus (center) , negatively charged out cloud, orbitals w/ electrons.

Atomic Mass

the amount of protons + neutrons.

atomic number

the number of protons in a nucleus

valence electrons

the electrons w/ the highest energy ( the ones on the outside orbital)

chemical bonds

the force of attraction that holds atoms together as a result of the reagargenment of electrons between them.

ions

is an atom or a group of atoms that have an electric charge (ex: Br-1)

ionic bond

is the attraction between two oppositely charged ions

covalent bond

a bond formed when 2 atoms share electrons

polar bond

a covalent bond when the electrons are not being equally shared

nonpolar bond

a covalent bond when the electrons are being shared equally

metallic bond

an attraction between a positive metal ion and surrounding electrons

element

a substance that cannot be broken down into any other substances by chemical or physical means.

molecule

a group of 2 or more atoms held together by chemical bond (s)

chemical formula

Heterogeneous mixtures

you can usually see the different parts and can easily be separated (ex: salad)

homogeneous mixtures

evenly mixed, you can't see the different parts and it is hard to seperate (ex:soy sauce)

physical change

alters the form or appearance of the matter but doesnt turn the substance in the matter into a different substance.

chemical change

a change in matter that produces one or more new substances.

Law of Conservation of Mass

,atter cannot be created or destroyed in any chemical or physical change.

isotopes

atoms of the same element with different number of neutrons [(no charge) ex : uranium-235 and uranium-238 atom ]

reactants

substances that undergo a chemical change

products

the new substances formed from the reactant

exothermic change

energy is released

endothermic change

energy is absorbed

pH scale

range of 0-14 indcates concentration of H+ ions in a solution
bases produce 0H- in water (more than seven)
acids produce H+ ions in water (less than seven)
even amounts of OH- and H+ = water = neutral